The apparatus of the invention is for use with modern high speed, high production printing or copying machines such as are used today in businesses, schools and the like. In the operation of these machines, the printed material, be it single sheets or multiple sheets such as pamphlets or brochures bound together by stapling, quickly accumulate in a stack at the exit bin of the machine. These bins fill to a predetermined stack height, after which the machine automatically terminates further printing until this stack is removed. This occurs in a rather short time so that the diligent effort of an attendant is required in order to get the maximum use and efficiency from the machine. This of course is even a more significant problem when these machines are ganged as in a large printing facility.
The apparatus of the present invention greatly diminishes the attention required by the attendant, in that with the invention, the stack of printed material is automatically removed from the exit bin of the machine and deposited on a conveyor where several stacks of the material may be stored before it is necessary that they be removed by the attendant.
While various apparatus are known in the prior art for mechanically conveying material, be it stacked or otherwise, and for retrieving material from one location and depositing the same in another, none of these apparatus is suitable for the purposes of the present invention. For example, U.S. Pat. Nos. 4,286,422 and 4,928,811 both disclose walking beam conveyor designs for moving material along a horizontal path by means of a group of beams or transfer elements that first elevate the material and then move it forward a predetermined distance after which they are lowered to deposit the material on elements that will retain it in this location while the beams or transfer elements are moved back to their original position where they will again engage the material, elevate the same and move it forward another predetermined distance. These devices are not suitable for the present invention. U.S. Pat. Nos. 2,896,946, 4,314,403 and 4,919,589 all disclose various designs of transfer apparatus for transferring stacked material from one location to another as from one conveyor to another. In the U.S. Pat. Nos. 2,896,946 and 4,919,589 , the transfer devices are so organized that the stack material is rotated 90 degrees so that it is transformed from a horizontal to an on edge position with support arrangements being required to keep it in the on edge position. In the U.S. Pat. No. 4,314,403 , the transfer device is effective to transfer plates from one conveyor to another where they are stacked, but the rotary transfer apparatus is such that the plates themselves must be rigid since they are lifted by apparatus that engages each edge of the plate. These apparatuses are accordingly likewise unsuitable for the present invention.